Heterocyclic Electrolyte for Lithium-Sulfur Cycle Life Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium-sulfur batteries face issues with deteriorated lifetime characteristics and lithium cycle efficiency due to the use of ether-based solvents, which lead to polysulfide leaching, dendrite growth, and increased viscosity during charging/discharging, limiting their application in high-energy density requirements for electric vehicles and energy storage systems.
Innovation Solution
An electrolyte solution for lithium-sulfur batteries comprising a first solvent with heterocyclic compounds containing double bonds and oxygen/sulfur atoms, a second solvent with ether-based, ester-based, or carbonate-based compounds, lithium salts, lithium nitrate, and borate-based lithium salts, forming a protective film to suppress polysulfide leaching and enhance ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ether-based solvent is used to improve sulfur reactivity, then lithium polysulfide dissolution is enhanced, but lifetime characteristics deteriorate due to polysulfide leaching and dendrite growth
Solution Approach 1:
The patent introduces a novel ether-based solvent with specific molecular structure (cyclic ether with oxygen atom in the ring) as an intermediary substance. This solvent mediates between sulfur polysulfides and lithium ions, enabling effective dissolution and reaction while the cyclic structure provides resistance to polysulfide leaching, thus resolving the contradiction between reactivity enhancement and lifetime deterioration
Solution Approach 2:
The patent changes the chemical parameters of the ether-based solvent by specifying particular cyclic ether structures with defined molecular weights and ring sizes. This parameter optimization allows the solvent to maintain high polysulfide solubility while the cyclic structure prevents excessive polysulfide extraction, thereby improving both reactivity and lifetime characteristics simultaneously
2Quantity of substance
If electrolyte solution content is decreased to achieve high energy density, then energy storage capacity increases, but viscosity increases rapidly during charging/discharging causing overvoltage
Solution Approach 1:
The patent optimizes the molecular weight and structural parameters of the cyclic ether solvent to achieve the desired balance. By selecting specific cyclic ether compounds with appropriate molecular weights and ring structures, the electrolyte maintains low viscosity even at reduced concentrations, preventing overvoltage while achieving high energy density
Solution Approach 2:
The patent creates a composite electrolyte system by combining the novel cyclic ether-based solvent with lithium salt and other additives. This composite formulation ensures that the electrolyte maintains optimal conductivity and low viscosity characteristics even when the overall electrolyte content is reduced for high energy density applications
3Quantity of substance
If conventional ether-based solvent is used, then lithium polysulfide solubility is high, but decomposition occurs leading to by-product deposition
Solution Approach 1:
The patent employs a specifically designed cyclic ether solvent that acts as a sacrificial protective medium. The solvent preferentially reacts with and stabilizes lithium polysulfides through coordination, preventing their decomposition into harmful by-products. The solvent molecules form stable complexes with polysulfides, effectively protecting them from degradation while maintaining high solubility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the lifetime characteristics and lithium cycle efficiency of lithium-sulfur batteries by reducing polysulfide leaching and dendrite formation, maintaining stable conductivity, and extending cycle life.
Implementation Method 1
incorporating a first solvent comprising a heterocyclic compound containing one or more double bonds and at the same time, containing any one of an oxygen atom and a sulfur atom... forming a protective film to suppress polysulfide leaching and enhance ion conductivity
Implementation Method 2
The lithium cation produced by the oxidation reaction of lithium is transferred to the positive electrode through the electrolyte
Implementation Method 3
lithium salt, wherein the lithium salt is at least one selected from the group consisting of LiCl, LiBr, LiI, LiClO4, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (C2F5SO2)2NLi, (SO2F)2NLi, (CF3SO2)3CLi, and lithium lower aliphatic carboxylate having 4 or less carbon atoms
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to an electrolyte solution for a lithium-sulfur battery comprising a first solvent comprising a heterocyclic compound containing one or more double bonds and at the same time, containing any one of an oxygen atom and a sulfur atom; a second solvent comprising at least one of an ether-based compound, an ester-based compound, an amide-based compound, and a carbonate-based compound; lithium salt; lithium nitrate; and borate-based lithium salt, and a lithium-sulfur battery comprising the same.